About Vincent Verweij

Vincent Verweij has been an urban forester with the Department of Parks and Recreation for three years. He has experience in topics beyond urban forestry, with geographic information systems (GIS), stormwater, flood management and engineering. His current work with Arlington ranges from tree inspections to plan review to restoration of natural areas. One of the goals of Vincent’s work is to maintain the County’s 40 percent tree canopy target in the long term.

Previously, Vincent worked with a federal contractor, performing tree canopy assessments and creating flood maps with GIS. Prior to that he worked at an arboretum mapping trees, and he has a long history working with nonprofit tree planting organizations. Vincent has an undergraduate degree in geography from The Ohio State University and a master’s degree in natural resources management from Virginia Tech.

What are Champion trees?

Measuring Champion trees (Source: Mississippi Champion trees)

Champion trees are the largest of its kind, in that species. Some species, like oaks and maples, get much larger than species like dogwoods and serviceberries, so we measure each species in its own class.

Measurement is done by professionals and volunteers all over the state. They involve three key measurements:

Height of the tree from the base to the top

Circumference of the trunk at 4.5 feet (also known as circumference at breast height, CBH)

The average width of the crown.

One adds the height, the circumference, and 1/4 of the canopy spread. This gives you a number, which you can compare with other large trees, to see if it’s the largest in the county, state, or nation.

State Champion Dawn Redwood

Does Arlington have Champion trees?

Because we have such dedicated volunteers, and a strong history in preserving trees, Arlington has some amazing champion trees, including state champions and one national champion! One tree we recently re-measured is the state champion Dawn Redwood (http://bigtree.cnre.vt.edu/detail.cfm?AutofieldforPrimaryKey=1838), which is a whopping 114 ft tall, and has a giant trunk. This tree is native to China, but finds our soil to be as suitable as its home country. Like our native baldcypress, it’s a deciduous conifer, and loses its leaves in the winter. Check out the picture on the left for this beauty, which can’t even fit in a single picture.

Where can I find them?

We have 1 National Co-champion (a Dwarf Hackberry), 49 State Champions, and 59 County champion trees. While some trees are on private property, and you need permission to view them, many of them are on county land. Check out the maps and registers below, for locations and more information:

Our country got hit by some extreme weather this year, with Hurricanes Harvey, Irma, and Jose hitting different parts of the country. We have luckily been spared from these storms, but have had to deal with major storms in the past.

The Department of Parks and Recreation has forestry staff, including a tree crew, certified arborists, and we work with other parks and Department of Environmental Services staff to address storm risks. This is an outline of some of the work we do to work with impending storms.

Prepare

We have over 700,000 trees in the county, with 19,000 of them being along streets, and most of them being near homes and other “targets”, which may be impacted by tree failure.

The Department of Parks and Natural Resources, particularly the Forestry section, works together with other departments, to prepare for the likely tree failure from oncoming storms by:

Monitoring storm paths

Preparing staff and equipment

Working with contractors for assistance beyond our reach

Setting up communication lines for residents, staff, and emergency responders to report downed trees and other issues

Bucket truck used to remove trees

Respond

During the storm, we typically:

Send out rovers to spot issues on our major roads, to make sure critical places such as hospitals and shelters are accessible.

Take requests from all sources, and map the severity and locations of these requests

Prioritize requests

Send out our tree crew and trades staff, and dispatch contractors for tree removals, when it is safe to do work.

Health benefits of trees

Recent studies have shown that sometimes, going to a park, or even looking a single tree can significantly improve a person’s health and stress levels. Some doctors have started prescribing parks as a remedy to patients’ health issues, and our tree values have been expanded to include mental and physical health benefits. While this is intuitive to tree lovers, seeing these studies can help us communicate the value of trees more.

Air quality and climate mitigation

Our trees are critical in filtering our air, removing harmful pollutants, such as Carbon Monoxide (toxic at high levels), particulate matter (causes asthma), and Ground-level Ozone (various respiratory impacts). See the image on the right.

Trees Improve Air Quality (Source: Nature Conservancy)

Water quality

As previously discussed in our stormwater post, trees filter drinking water for us and the creatures with which we share the world.

Mental health

A less-reported value of trees are their mental health benefits, but these can outweigh many of the others, shown through many studies (links below):

Improved memory

Reduced hospital time and improved recovery, from a view of green or treed space

Increased attention level in children

Increase social cohesion of communities

Trees and health (Source: ACTrees)

Shade

Heat is one of the greatest impact on urban health, and trees, through shade and transpiration, can greatly reduce heat-related illness and comfort. Trees can reduce ambient heat by up to 9 degrees Fahrenheit, compared to exposed areas.

Crime

The folklore of trees providing hiding spots for crime is largely negated by modern research, which shows trees can greatly improve crime statistics in neighborhoods. Controlled for social background, areas with vegetation and healthy trees performed much better than unvegetated areas. In one study, vegetated areas had 7 to 8 percent less gun-related incidents than the control area. This most likely links with the mental health benefits of trees, but is good to take into account when planning a city.

Our community’s trees overall health benefits

Our i-Tree study provides us with actual number values of some of these benefits, and in Arlington, our trees provide us with the following health benefits:

Number of trees: 755,400 (45 trees/acre, a healthy natural forest has 40-60 trees/acre)

Trees as a Filter

Bluemont Forest Buffer

Arlington County recently installed its first forest buffer as a stormwater Best Management Practice (BMP) at Bluemont Park’s new baseball field. This forest buffer not only looks great, but also serves an important function for this park and our community.

To help improve the Chesapeake Bay Watershed, and the water we depend on, trees are being used on larger projects that allow water to flow into a forest or forest buffer. The trees improve our water in many ways, along with providing other benefits of air pollution control, shade, beauty and wildlife benefit.

The First Rain: Interception and Evaporation

Every tree catches the rain as it comes down, but did you know a mature White Oak (Quercus alba) can intercept up to 12,010 Gallons of water every year? That’s just a single tree! This water stays in the leaves until it’s absorbed by the tree or evaporates to cool our air. This is the first line of defense, as this prevents this water from needing to be piped or treated by other stormwater infrastructure. According to our i-Tree Eco study, our trees in Arlington alone capture 80,267,230 gallons every year!

Stormwater Benefits of Trees: Source: Deeproot

Keeping it in the Soil and Filtering: Infiltration and Storage

Trees are designed by evolution to make the best use of every drop that falls on their canopy. Their leaves and branches act like a giant capturing device to get precious water to the tree’s roots. This helps trees provide one of the greatest stormwater benefits: infiltration and storage. Through filtering the water with their roots and soil, pollutants get trapped and diluted which reduces the impact of water pollution.

Additionally, storing all this water makes it available for the tree and other plants around it. This stored water can then be used to grow the tree and evaporate this water back into the air, once more preventing it from impacting our stormwater system.

Forest Buffers as a Stormwater Device

In the case of Bluemont’s baseball field, there were some restrictions to using this tool, but it was perfect for this project. These are some of the restrictions to using forest buffers for stormwater credit:

You need a fairly flat slope and space to accommodate the water to slowly flow through

Very flat slopes (1-4%) can use a 35 ft buffer

Moderately flat slopes (4-6%) need 50 ft

Steeper slopes (6-8%) need 65 ft

Soils must be able to drain and store the water

Wider Benefits

These solutions can have a great positive impact on our community and has many benefits over traditional stormwater infrastructure:

This technique is a non-engineered, nature-based solution to stormwater

A short history of Arbor Day

Arbor day was founded by J. Sterling Morton, in Nebraska, to spread the value of trees to all communities. On the first arbor day, over a million trees were planted. It continues today as one of the few holidays that looks optimistically towards the future, and over 3,400 communities have become Tree City USA, a recognition bestowed on communities supporting trees and forestry. Arlington is one of these communities, and we recently celebrated our 21st Arbor Day, and 13th year of the Arbor Day Growth Award.

Every year, we apply to stay recognized as a Tree City USA. This requires us to:

Have a tree board and department in charge of taking care of our urban forest. This is met by our Urban Forestry Commission, and our Urban forestry unit

Enforce a tree care ordinance, to take care of and protect our public trees.

An annual forestry budget of at least $2 per capita per year.

An arbor day proclamation and observance

The arbor day celebration is always one of the most fun part of the forester’s jobs, as it is usually held at a school, with music, poetry, and a tree planting, with support from our landscape unit.

Tree City USA sign on Columbia Pike

Growth Award

It is optional to apply for an additional recognition of the Growth award. This award is given to communities who go beyond the call of duty to improve their programs, through expanded education, partnerships, increased planning efforts, or additional tree planting and maintenance funding.

Arlington has received the growth award for 13 years, and will continue to seek this award, as one of the leading communities in urban forestry in the region. Last year, we added an urban forestry manager position, and completed the i-Tree Eco study.

More information

Figuring out where all the trees in Arlington are, and what species they all are sounds like a daunting task. Luckily, Urban Forestry got help from the U.S. Forest Service, with i-Tree Eco. This free program uses statistical sampling to understand the composition and value of a community’s Urban forest. Check out what we found out about Arlington’s impressive tree canopy!

How many trees?

Tree species Distribution

Let’s get right to the point. Through a statistical plot measurement program, we estimate Arlington County is home to 755,400 trees. That’s about 45 trees per acre. To compare this to a natural forest, a healthy forest has about 40-60 trees. This is why we call the forest in Arlington County an urban forest. We found 122 species of trees, most of them native to Arlington.. Our state tree, the Flowering dogwood, was the most common tree found, with the Tuliptree covering the most of our overall tree canopy.

What are the environmental benefits of all these trees?

Environmental Benefits of Arlington trees

While the beauty of trees is one of the more obvious values of our urban forest, trees provide a wide range of ecosystem services. From stormwater reduction, reducing the chance of flooding, to improving our health, through filtering air pollutants and slowing down the effects of climate change through carbon sequestration and shading, these benefits were quantified by the i-Tree Eco study.

Did you know that, every year, our trees prevent 10,730,168 Cubic feet of water from flooding our community? That’s about 122 Olympic-sized swimming pools every year! That’s just one of the benefits included in the almost $7 million yearly benefits we get from trees. Check out more of them on the left.

How did we do this?

Throughout 2016, Urban Forestry staff worked with volunteers from the Tree Stewards and Master Naturalists, looking at 201 1/10 Acre plots throughout the county. We recorded information on the plot characteristics, species in the plot, sizes of trees, and their effect on the direct environment. This information was processed by the US Forest Service servers, and put in context.

Urban forestry is still analyzing much of the results, but these preliminary results are exciting for use in managing our urban forest to ensure high diversity of tree species, manage for tree care budget needs, and help communicate the value of our urban forest.

Fruit and nut trees for Arlington County

Growing and harvesting fruit and nuts from your own trees can be one of the most fulfilling and rewarding things to do on your property. This article talks about the considerations for working with these plants in and around Arlington County. Here are some quick tips on how to select for fruit trees:

What can grow here?

Climate: In Arlington, we live in hardiness zone 7b. That means species that don’t to

Fresh Pawpaws!

lerate our climate are outside of our range. For example, citrus fruit, coconuts, and other more southern fruits will not likely survive or thrive in our community. Many trees can do well in warmer micro-climates in cities, where they would not thrive in the suburbs. Figs are a prime example of this.

Adaptability to our soils: Our soils tend to be fairly acidic. Not every fruit or nut tree likes that condition. Native fruit trees can be perfect for these conditions, but many fruit and nut trees can tolerate our soils, as well. Check the label before buying. Just because it’s sold here, doesn’t mean it will do well!

Check the handout for our presentation for a list of fruits that grow in this region.

How much work can you put into the trees?

Pruning: Many fruit trees require pruning for a full harvest. Consider the work involved in this, and how you can accommodate this at your home

Pest management: Most fruit and nut trees have developed some nasty diseases, after millenia of cultivation. Some may require chemical or organic pest control. Pick pest-resistant species, or be prepared to spend some time on pest control.

Soil improvement: Not all soil is perfect for growing fruit and nut trees. If you’re dead set on a species, you may have to amend or remediate your soil. Be aware that pollutants may concentrate in your fruit, as well, so always have your soil tested before planning an urban agriculture adventure.

What to avoid

Species susceptible to disease: Check with your local extension (http://offices.ext.vt.edu/arlington/ ) to determine appropriate species for pest resistance in our area.

Invasive species: Non-native invasive species, such as white mulberry may be tasty, but can cause significant ecological impacts. See the handout for a short list of trees to avoid.

What exactly am I going to do with 100 apples at the same time? It may sound great to grow apples in your yard, but if you do not have a good plan for all the fruit that will grow in your new orchard, it may become a bigger mess than a benefit. Consider options like canning, dehydrating, and juicing before it’s too late, so you’re prepared to handle a barrel of delicious fruit, because even the most delicious fruit gets tiring after a couple of days.

When trees get transplanted, they lose significant portions of their roots, and need time to get used to their new planting location. Below are some guidelines on what to do to establish new trees in Arlington County’s climate, and when you should think of watering older trees:

Watering new trees

Watering bag on tree

During the growing season, newly planted landscape-size trees (usually 1-2 inches in diameter at the trunk, or about 8 ft high), prefer to get watered about 25 gallons every week. Of course when we have heavy rains, this is less necessary, but Arlington often has periods of relative drought, in the later summer, when watering becomes crucial for trees.

Unlike grass or other smaller plants, trees prefer slower watering, over a longer period of time. Here are some options for watering:

Use a watering bag (see image on the right), and follow the directions on the bag to make sure it drains properly. Remove the bags over the winter.

Lay a hose at the base of the tree, and let it flow at a low volume for about 30 minutes, before turning it off.

Use surface irrigation, around the base of the tree. Be careful to remove irrigation after the tree is established.

For a video on watering, check out Casey Trees’ watering video:

Watering older trees

Older trees may have established roots, and good access to water, but in cases of extreme drought, they can really benefit from extra water. Here are some options that work:

Lay a hose at the base of the tree, and water at low pressure for up to 1 hour.

Combine watering bags around the trunk of the tree, and fill these with water. Be sure to remove these after the dry season, as they can introduce decay in the trunk, if left on.

When do I water?

It is generally recommended that if less than 1 inch of rain has been recorded locally in a whole week, to water your trees. You can use the National Weather Service website to track precipitation:

http://w1.weather.gov/data/obhistory/KDCA.html

Another great resource are the Casey Trees watering alerts, which are posted on their website every week: http://caseytrees.org/

After the explosion of the cherry blossoms, magnolias, serviceberries, catalpas, and other showy flowers, summer often feels like an aesthetic drought because most of the trees are done blooming. But there is a subtle beauty that will never leave you once you notice it. Young leaves coming through in mid to late spring, throughout the summer, with second flushes, and the fully formed leaves are a wonder to behold. Green is a deceptive color, as it often blends with its surroundings, but the shapes of leaves are just as diverse as flowers in their creativity.

Young leaves

Young white oak leaves

Early emerging leaves, and leaves that come to trees as they go through multiple flushes of leaves (like black cherry (Prunus serotina), for example, whose early leaves are often defoliated by tent caterpillars) are little works of art. Oak leaves in large masses are impressive on the tree, but every large oak leaf starts out as an intense concentrated red (see the young white oak (Quercus alba) leaves on the right). These leaves have significant amounts of anthocyanins, natural chemicals that act as sunscreen, giving it the color. These colors dominate before the green chlorophyll, the pigments that help in converting sunlight into food, takes over.

Young tuliptree leaves

Other leaves are fascinating for how they unfold. The cat-face-shaped Tuliptree (Liriodendron tulipifera,on the left) leaves are folded up in a tiny package, released with the early flowers, and unfolding over several weeks in spring, before starting to develop. This efficiency in packaging is unrivaled in even the most efficient engineered electronics packaging, and surpasses it in elegance.

Nature keeps it weird

Sassafras leaves

Even after the young leaves unfold acrobatically, they remain their mysterious shapes and continue to astound us in their diversity. One of my favorites remains the versatile Sassafras (Sassafras albidum). A tree historically used to create flavors in root beer, as well as medicinal applications, the leaves have a variety of mitten and heart shapes. The picture on the right shows some of the red the leaves also hold onto throughout the season, and the more regular shape they hold.

Ginkgo Leaf

One of the most recognizable leaf shapes is the non-native Ginkgo (Ginkgo biloba,on the left). This leaf shape often shows up in fashion patterns, jewelry designs, and more. While the tree is considered to be a living fossil (with no real wildlife value or typical ecological niche), it’s a great ornamental tree that is urban hardy, with fascinating leaf shapes, and an amazing fall color display. This tree is a conifer although it looks like a broadleaf tree. The conifer aspect is best displayed when it drops all of its leaves at the same time in the fall (common with deciduous conifers). Although it’s spindly branch shape, and elegant fan-shaped leaves remain throughout the year.

More on leaves.

This just highlights a handful of trees of the hundreds of trees native and planted in our area. Here are some great resources for exploring our tree diversity:

In our Natural Arlington blog, we’ve talked previously about the studies done on tree canopies. This gives us a great idea of the extent of where our trees are in the county. However, it does not communicate what kinds of trees Arlington has, their ecological value, and the age distribution. This information is invaluable to managing our tree canopies properly, and we will be surveying plots throughout the county using the United States Forest Service (USFS) program iTree Eco.

What is iTree Eco?

The USFS describes this program as “a software application designed to use field data from complete inventories or randomly located plots throughout a community along with local hourly air pollution and meteorological data to quantify urban forest structure, environmental effects, and value to communities.”

What this means in practice is we will be performing 201 plot surveys of trees, of 0.1 acre in size, throughout Arlington County. These surveys will provide us with a statistic estimate on the greater value and composition of our tree canopies. For example, we will learn how complete our vertical tree canopy is, with all the components described earlier in the Designing a forest from the ground up post.

iTree Eco plot example

What will we be doing this year?

Staff and volunteers will be going out to all the plots (such as the plot on the left), and assess the composition of the plot, including: